Hoisting apparatus



y 28, 1 c. A. MARTIN 2,400,939

HOI S TING APPARATUS Filed Nov. 5', 1944 3 Sheets-Sheet l 64 0v INYENTOR w ATTORNEYJ,

May 28, 1946; MA IN 2,400,939

HOISTING APPARATUS v Filed Nov. 3, 1944 3 Sheets-Sheet 2 ATTORNEY-7 C. A. MARTIN HOISTING APPARATUS Filed Nov. 3 1 944 a Sheets-Sheet 5 ATTQRNEYJ Patented May 28, 1946 UNITED STATES PATENT OFFICE 2,400,939 HOISTING APPARATUS Charles A. Martin, Buffalo, N". Y; 7 Application November 3, 1944, Serial No.56 1,707

(o1. sir-100i 12 Claims.

This invention relates to a hoisting apparatus of the general character shown in Letter Patent of the United States No. 2,297,572, granted September 29; 1942, and the present invention embodiesseveral improvements on this prior construction.

It has been found b actual experience that slabs, sheets, planks or boards which are intended to be used in the construction of a building, vary considerably in width, depending on the charac-' ter ofthe product, and it is therefore one of the objects of this invention to provide means whereby the supporting surface of the elevating carriage of a hoisting apparatus may be either increased or decreased in length as best suits the particular Width of the building materialwhich-is to be hoisted and thereby enable the apparatus to handle the material safely and efiiciently.

In this prior apparatus, means were provided for retaining the load on the lifting platform-by engaging the front end of the load with a relatively stationary part of the apparatus until the load was raisedto the level of a delivery platform at which point the load was automatically discharged from the lifting platform to the delivery platform preparatory tobeing carried away by the workmen to wherever the same wasrequiredon the'job. This engagement of the rear end of the load is objectionable on accountof the frictional resistance which required more power to elevate the load and also on account of marring the rear end of the load by engagement with the relatively stationary parts against which the load rubbeddurlng its ascent.

Afurther object of this invention is to provide a stop or retaining mechanism at therear side of the lifting platform and carriage which is so organized that during the elevation of the load, the same will be prevented from rubbing against any stationary surface during its elevation and which permitsthe load, upon reaching the-level of the delivery platform'or place of'discharge at the top of the apparatus, to automatically release the load on the lifting platform and permit the same to move rearwardly therefrom onto the de livery platform.

Additional objects of this invention are to provide means whereby the above mentionedpurposes are accomplished in a manner which will facilitate the elevation of loads ofth'e character referred to and discharge the same to upper parts of a building which is under construction expedi tiously and'with'out liability of injuring any ofthe working parts so that undue interruption of Work is avoided.

. of the lifting platform, delivery platformand In the a'coonipanyingdrawings:

Fig. 1 -is a side elevation-ofa=hoisting apparatus embodying this invention and showirig'the parts in a position in which the elevating carriage and-lifting platform ar-raised one level with the delivery platform and a' -lo a d ofahate'rial such-as a building-slab,- plank' ol board of' considerable width' is bein'g discharged f-ionithlift ingplatform to the delivery platform:-

Fig. 2 is a top plan view; ori-aneiilarged seale,

the stop or retaining mechanism associated therewithforl controlling the movement of the ing platform to thedeliv'ery platform;

Fig; 4 is a fragmentary'verticallongitudinal section taken on line 4-4; Fig; 2'andshowing the liftingplatform arranged on a level with the'delivery platform and the-automatic stop or'retain ing device in a'posltion in which the= stop elements of the same are moved downwardly below the path ofthe'load and permitthesame'to move from the lifting-platformto the deliveryplat-' form.

Fig. 5'is"a sectionsimilarto Fig; 4,- but'showing the elevating carriage and liftingfplatform in a position below the level of the deliveryplatform and the load retainingrmechanism' in a position in which its stop elements projectupwardly-at the rear side *of the lifting platform and into the path of=the load which is beinglelevated for preventing the latter from' engagingwith any relatively stationary surface or parts of' the apparatus.

Fig. 6 isa fragmentary view-similar to Figs. 4

and 5; but showing the auxiliaryor front section of the" lifting platform" lowered into an inoperative' position relative to the 'rear' or main section ofthis platformtothereby-adapt the apparatus more particularlyrfor handling a load of narrow width.

In the followingdescription -similar' characters of reference-indicate like parts-in the seve'ral-figures of the'drawingsj The main" frame of the hoisting apparatus which 'supports themovable partsmomprises um right standards-bars or rails" [0 which rest-at theielower" eiids on the ground; II and lean toward tlie build-in'g I 2 on whi'eli the work is bemesons: As shot/nan Fig-S- 1, the main frame is supported in an inclined position by engagement of lugs 25 on the upper rearyparts ofthe rails l8 with the cornice or roof 13 of the building. Each of the standards it is channel shaped in cross section, and has its hollow side facing outwardly so as to form a vertical guide way it for the elevating carriage which is adapted to move vertically on this frame.

At its upper end the main frame is provided with a delivery platform which projects rearwardly therefrom in an inclined position over the adjacent roof portion of the building and is adapted to receive the load 2! from the elevating mechanism. This delivery platform preferably comprises two longitudinal rows of horizontal conveyer rollers E5, the rows being spaced apart transversely and the rollers in each row having their opposite ends pivoted in a pair of outer and inner longitudinal frame bars Ni, ii. The rear ends of the longitudinal bars i6, ll of the two rows of delivery rollers are connected by a rear cross bar l8 and at their front ends the two inner longitudinal bars it are connected by a front cross bar. l9.

The front end of each outer longitudinal bar it is spaced from the adjacent end of the front cross bar 19 by a gap or clearance space 20 for a purpose which will be described later on. Intermediate each pair of longitudinal bars l6, ll the front and rear cross bars l9, it are connected by additional longitudinal bars 35, 35.

The bars l6, ll, l8, and i9, form the frame of the delivery platform and this is pivoted at its front end by bolts 22 to the upper ends of the main frame standards or rails Ill so that this platform can be turned vertically for changing the angularityof its upper load supporting surface. The angularity of the delivery platform may be adjusted by substantially the same means which are shown in the patent referred to and which include upright adjusting bars 23 pivoted at their upper ends to the rear ends of the bars 35 and adjusting bolts 24 mounted on lugs 25 projecting rearwardly from the standards 101 and passing through slots 26 in the adjusting bars 23.

The carriage. which moves vertically on the main frame and supports the load 2! which is to be lifted, may be variously constructed but preferably comprises two upright side sections which are arranged along the outer sides of the upright bars, rails or standards it of the main frame and a horizontal cross connection whereby these twoside sections are connected, similar to the carriage shown in the patent above referred to.

Each of these side sections comprises a vertical bar 21 which is provided at its upper and lower ends with guide rollers 28, 29 moving in the guide way or track is on the outer side of the adjacent main frame rail, an upper horizontal bar 3!! pivoted by a bolt 3 on the upper end of the vertical bar 21 and extending forwardly therefrom and an adjustable inclined bar 3i which is pivoted by a bolt 33 to the front end of the horizontal bar 30 and pivoted at its lower end to the lower end of the vertical bar 21 by a bolt 36, as shown in Figs. 1, 4 and 5. The cross connection between the two side sections of the carriage includes a horizontal cross bar 32 which is secured to the lower parts of the inclined bars SI of the two side sections of the carriage. By lengthening or shortening the inclined bars iii of the carriageside sections, the upper horizontal bars 38 of the same may be turned vertically about the pivotal connections 34 between the same and the vertical bars 2'! for the purpose of changing the angularity of these horizontal bars 30 together with the load and the means whereby the same is supported on the upper part of the carriage.

The downward movement of the carriage on the main frame is effected by gravity and the upward movement of the same thereon is effected by means which include a hoisting line passing with its upper part around an upper hoisting pulley 3i and having a front stretch 38 the lower end of which is attached to the cross bar 32 of the carriage and a rear stretch .39 extending downwardly and around a lower hoisting pulley M on the lower part of the main frame where the same may be pulled manually or by power means of any suitable character.

Above the lifting carriage is arranged a lifting platform which preferably comprises a rear section which is permanently connected with the upper part of the carriage and a front or auxiliary section which is adjustably connected with the rear section so that the front section may be moved into and out of an operative position for the purpose of adapting this lifting platform to different widths of material which is to be lifted.

The rear section of the lifting platform preferably comprises two longitudinal rows of conveyer rollers ll, ll which are spaced apart transversely and arranged in front of the conveyer rollers on the delivery platform. The rollers of each row of the rear lifting platform section are pivoted at their inner and outer ends on a pair of inner and outer longitudinal frame bars 12, 22, the rear ends of which are connected by a rear cross bar 44 and the front ends of the same being connected by a front cross bar 45. The longitudinal bars 42, 43 and the cross bars M, 55 form the frame of the rear platform section and thisrframe is connected with two supporting lugs H5 rising from the rear part of the horizontal bars of the carriage side sections and with two supporting lugs 41 projecting upwardly from the front parts of these carriage bars, as

shown in Figs. 1, 4, 5 and 6.

The front section of the lifting platform comprises a frame having a front cross bar 48 which is arranged in front of the rear lifting frame and two longitudinal side bars 49, 49 which are connected at their front ends with the opposite ends of the cross bar 48 and have their rear ends pivotally connected with the outer bars of the rear lifting frame by means of pivot bolts 50. The numeral 5i represents two short lugs projecting rearwardly from the cross bar 48. Between each of these lugs and the companion outer longitudinal bar 49 is arranged a horizontal conveyer roller 52 which has its opposite ends pivoted on said lug and side bar, as shown in Figs. 2, 4, 5 and 6. When the front section of the lifting platform is in use, the same is elevated into a position in which the upper surface of its conveyer rollers is in line with the corresponding surfaces of the conveyer rollers of the rear lifting frame section, as shown in Figs. 2, 4 and 5, but when this front section of the lifting platform is not required, the same is turned downwardly into a position in which it is arranged at an angle to the rear lifting platform section and depends therefrom, as shown in Fig. 6.

Means are provided for holding this front lifting platform section either in its operative elevated orin its inoperative depressed position,

which means in the preferred construction, comprise two adjusting bars each of which has an inclined body 53 pivoted at its upper end by means of a hinge 54 to the underside of the cross bar 38 and provided at its lower end with a forwardly bent lip 55 which is arranged at an angle relative to the body 53, and a fastening bolt 56 arranged on the upper part of the respective adjusting bar 3| and adapted to pass either through an opening in the bent lower end or lip 55 of the adjusting bar and hold the front lifting frame section in its elevated position, as shown in Figs. 1, 4, and 5, or through an opening in the upper part of the body of this bar and thereby hold the front lifting frame section in a downwardly inclined inoperative position, as shown in Fig. 6.

When elevating lumber, concrete slabs, boards or sheets of considerable width, the auxiliary or front section of the lifting platform is adjusted into its operative position in line with the companion rear section of this platform, as shown in Figs. 1, 4 and 5, thereby providing ample supporting surface for a wide load and avoiding undue overhanging of the front part of this load beyond the front side of the lifting platform. When, however, the width of the material to be raised is relatively narrow and the same can be properly supported on the rear section of the lifting platform without liability of the load tipping forwardly therefrom, the front lifting platform section is lowered into its inoperative position as shown in Fig. 6, thereby enabling the lifting platform to be loaded by the workmen more conveniently.

Retaining or stop means are provided which embody the present invention whereby the load, while being elevated, is retained on the lifting platform and prevented from engaging its front part with the main frame and the delivery platform or parts thereof but which release the load and permit the same to move from the lifting platform to the delivery platform whenthe latter is raised to the same level as the delivery platform. a

In its preferred form, this retaining mechanism operates automatically and is constructed as follows:

The numeral 5'! generally represents two retainin or stop levers which are spaced apart crosswise of the rear section of the lifting platform and each of which is preferably of angular form and comprises a comparatively long lower arm 53 arranged lengthwise below the rear part of the rear section of the lifting platform and some of the conveyer rollers thereof, an upper arm 59 projecting upwardly from the front end of the lower arm 58 and into the space between two of the conveyer rollers ii, a front arm 63 projecting forwardly from the lower end of the upper arm 59 and a stop member or finger 6| projecting upwardly from the rear end of the lower arm 58.

The upper arms 55 of the retaining levers terminate in line with the upper side of the several conveyer rollers of the lifting platform and these levers are pivoted so as to be capable of swinging vertically independently of each other by means of sleeves or hubs 62 arranged on the upper ends of the upper lever arms 59 and turning on a pivot rod t3 which is mounted horizontally and transversely on the frame of the rear lifting platform section, as shown in Figs. 2, 4 and 5.

In its operative position, each of the retaining levers is moved upwardly so that its stop finger 6| projects upwardly along the rear side of the rear lifting frame sectionand into the path of the building slab, plank or board which is resting on the conveyer rollers of the lifting platform, as shown by full lines in Fig. 5, thereby causing this load to be held against rearward longitudinal movement which otherwise would occur owing to the inclination of the upper sides of the several conveyer rollers 4|, 4|, 52.

When, however; the retaining levers are de pressed so their stop fingers 6! have their upper ends withdrawn below the upper sides of the conveyer rollers of the lifting platform, as shown by full lines in Fig. 4, then the load is released and free to move rearwardly by gravity from the lifting platform.

While the carriage and the lifting platform are moving upwardly and shortly before reaching their uppermost position, the retaining levers are arranged in their upper or operative position so that the load on the lifting platform is held against moving rearwardly therefrom and at this time, these lifting levers are yieldingl held in their operative position by spring means which preferably include two helical springs 64 each of which is arranged below the rear section of the lifting platform and has its front end connected with the rear cross bar 64 thereof while the front end of the respective spring is connected with the adjacent retaining lever. For the purpose of enabling the tension of each of the lifting springs as to be adjusted so as to exert the desired pull, the front end of each of these springs is connected with therear end of an adjusting bolt 65 and the threaded front end of this bolt projects through an opening in an abutment 66 formed on the front end of the lever arm 6!! and is pro vided with a screw nut 61 which engages with the front side of this abutment, as shown in Figs. 1, 4 and 5.

Upward movement of each of the retaining levers under the pull of its spring 64 is limited by engagement of the lower arm 58 of this lever with l the underside of the rear cross bar 44 of the rear lifting frame section, as shown in Fig. 5.

During the last part of the upward movement of the carriage and the lifting platform, the two retaining levers are moved downwardly by a tappet or trip mechanism so as to withdraw their stop fingers 6| out of the path of the load on the lifting platform by the time the upper sides of the conveyer rollers 4|, 52 come in line with the conveyer rollers I5.

The preferred means for causing each of the retaining levers to move into its inoperative position and releasing the load on the lifting platform are constructed as follows:

The numeral 68 represents a tappet which is mounted on the rear part of each of the retaining levers and projects rearwardly therefrom so that during the last part of the upward movement of the elevating carriage, this tappet will engage the underside of a stationary trip stop or abutment 69 which is arranged at the upper end of the main frame and preferably mounted on a cross bar 76 which forms part of the frame of the delivery platform.

In order to cause each of the retaining levers to be depressed at the right time when the conveyer rollers of the lifting platform are on a level with the conveyer rollers of the delivery platform, means are provided for adjusting each of the tappets relative to its respective retaining lever. These adjusting means, as best shown in Figs..2, 4 and 5, comprise a bolt 1| which pivotally connects the lower end of each tappet with the rear part of the companion retaining lever and an inclined adjusting link l2 which is pivoted at its upper end by a pivot bolt'13 on each of the stop fingers 5 l, and an adjusting bolt 14 which passes through the respective tappet and one or another of a longitudinal row of openings 15 in the lower part of the link 12. By raising or lowering the tappet 68 and then securing the same in the required position after such adjustment, the free end of this tappet will engage the trip stop 69 and insure withdrawal of the stop finger from the path of the load on the lifting platform when the latter reaches the delivery platform and thu permits the load on the lifting platform to be released and to move automatically by gravityfrom the lifting platform onto the delivery platform.

As the load slides from the lifting platform to the delivery platform, the same may be taken care of by the workmen, but if desired, this load may be transferred onto a receiving platform or bench which is mounted on the roof of the building under construction. This receiving platform, as shown in Fig. 1, may consist of a frame 16 provided with legs 1'! adapted to rest upon the roof of the building and also with conveyer rolL ers 18 which are in line with the conveyer rollers of the delivery platform so that the load will move freely by gravity from the lifting platform to the delivery platform and then onto the receiving platform.

In this organization, the stop fingers of the retaining levers move vertically into and out of the gaps 20 formed in the front side portion of the frame of the delivery platform, whereby the lifting and delivery platforms are arranged coinpactly and the automatic stop mechanism is arranged wholly within the boundaries of the elevating and delivery mechanisms, and the apparatus is not liable to be injured.

I claim as my invention:

1. A portable hoisting apparatus comprising an upright main frame, a delivery platform extending rearwardly from the upper end of said frame, a vertically movable carriage guided on said frame, and a lifting platform mounted on thecarriage and arranged on the front side of the frame and adapted to raise a load to said delivery platform and including a main rear section, an auxiliary front section which is pivotally connected with said main section and adapted to be turned upwardly in an operative position in line with said main section and downwardly into an inoperative pendent position relative to said mainsection, and adjusting means for securing said auxiliary section in either its operative or inoperative position, including an adjusting bar pivoted at its upper end to said auxiliary section, and a bolt for connecting said bar at different points in the length thereof with said carriage.

2. A portable hoisting apparatus comprising an upright frame, an inclined delivery platform extending rearwardly from the upper end of said frame and provided with conveying rollers, a vertically movable carriage guided on said frame, a rearwardly inclined lifting platform mounted on the carriage and arranged on the front side of the frame and adapted to carry a load to the delivery platform and including a rear main section mounted on the upper part of said carriage and. having conveying rollers and an inclined auxiliary front section pivoted at its rear end to the front end of said rear section and provided with conveying rollers, and adjusting means for holding said auxiliary section either in line with said main section or in a pendent position relativethereto including an upright adjusting bar having a straight upper body part which is pivoted at its upper end to the front part of said front section, and provided at its lower end with an inclined lip arranged at an angle to said body part, and a fastening bolt adapted to connect either said body part or said lip to said carriage.

3. A portable hoisting apparatu comprising an upright frame, a vertically movable carriage guided on said frame, a lifting platform for carrying a load mounted on said carriage and arranged on the front side of said frame, retaining means movable with said carriage and lifting platform and having a stop adapted to be engaged by the rear part of the load on the lifting platform and movable into and out of the path of the load from said lifting platform, spring means interposed between said retaining means and said lifting platform for yieldinglyholding said retaining means across the path of the load on the lifting platform until the latter has nearly reached its uppermost position, and a stop element arranged on the frame and adapted to be engaged by said retaining means when the lifting platform reaches its uppermost position for positively moving the retaining means out of the path of the load on the lifting platform.

4. A portable hoisting apparatus comprising an upright frame, a delivery platform inclining rearwardly from the upper end of said frame, a vertically movable carriage guided on said frame, a rearwardly inclined lifting platform mounted on said carriage and arranged on the front side of said frame and adapted to support a load to be raised into line with said delivery platform, retaining means moving with said carriage and lifting platform and having a part movable into and'out of the path of the load from said lifting platform to said delivery platform, spring means interposed between said retaining means and said lifting platform for yieldingly holding said retaining means across the path of the load on the lifting platform until the latter has nearly reached its uppermost position, and a stop element arranged on the frame and adapted to be engaged by said retaining means when the lifting platform reaches its uppermost position for positively moving the retaining means out of the path of the load on the lifting platform.

5. A portable hoisting apparatus comprising an upright frame, an inclined delivery platform at the upper end of the frame, a carriage movable vertically on the frame, an inclined lifting platform mounted on said carriage and arranged on the front side of said frame and adapted to support a load and raise the same to the level of the delivery platform, retaining mean on the lifting platform and having a stop part adapted to be engaged by the front part of the load on the lifting platform, and automatic means for actuating said retaining mean and withdrawing the stop part from the path of the load when the lifting platform reaches the delivery platform and permits the load to move by gravity from the lifting platform to the delivery platform, said automatic means including spring means interposed between said retaining means and said lifting platform for yieldingly holding 'said stop part across the path of the load on the lifting platform until the latter has nearly reached its uppermost position, and a stop element arranged on the frame and adapted to be engaged by said retaining means when the lifting platform is completing its upward movement and thereby causes the stop part of the retaining means to be moved out of the ing platform.

6. A portable hoisting apparatus comprising an upright frame, a rearwardly inclined delivery platform arranged at the upper end of the frame, a vertically movable carriage guided on the frame, a rearwardly inclined lifting platform mounted on the carriage, and arranged on the front side of the frame adapted to support a load, and retaining means for holding the load on the lifting platform while the same is being raised to the level of the delivery platform then permitting the same to move by gravity from the lifting platform to the delivery platform, including a stop finger movable vertically into and out of the path of the load at the rear side of the lifting platform, a vertically swinging lever pivoted at its front end on the lifting platform carrying said finger at its rear end, yielding shifting means for holding the lever in a position in which its stop finger projects across the path of the load on the lifting platform, a tappet connected with said lever, and a trip stop connected with the frame and adapted to be engaged by said tappet to move said lever in a direction for withdrawing the stop finger out of the path of the load from the lifting platform to said delivery platform.

7. A portable hoisting apparatus comprising an upright frame, a rearwardly inclined delivery platform arranged at the upper end of the frame, a vertically movable carriage guided on the frame, a rearwardly inclined lifting platform mounted on the carriage, and arranged on the front side of the frame and adapted to support a load, and retaining mean for holding the load on the lifting platform while the same is being raised to the level of the delivery platform and then permitting the same to move by gravity from the lifting platform to the delivery platform, including a stop finger movable vertically into and out of the path of the load at the rear side of the lifting platform, a vertically swinging lever pivoted at its front end on the lifting platform and carrying said finger at its rear end, yielding shifting means for holding the lever in a position in which its stop finger projects across the path of the load on the lifting platform, a tappet connected with said lever, a trip stop connected with the frame and adapted to be engaged by said tappet to move said lever in a direction for withdrawing the stop finger out of the path of the load from the lifting platform to said delivery platform, and means for adjusting the position of said tappet relative to said lever and trip stop.

8. A portable hoisting apparatus comprising an upright frame, a rearwardly inclined delivery platform arranged at the upper end of the frame, a Vertically movable carriage guided on the frame, a rearwardly inclined lifting platform mounted on the carriage, and arran ed on the front side of the frame and adapted to support a load, and retaining means for holding the load on the lifting platform while the same is being raised to the level of the delivery platform and then permitting the same to move by gravity from the lifting platform to the delivery platform, including, a stop finger movable vertically into and out of the path of the load at the rear side of the lifting platform, a vertically swingin lever pivoted at its front end On the lifting platform and carrying said finger at its rear end, yielding shifting means for holding the lever in a position in which its stop finger projects across the path of the load on the lifting platform, a tappet connected with path of the load on the lift- ,said lever, a trip stop connected with the frame adjusting the position of said tappet relative to said lever and trip stop including a pivot conneoting said tappet with said lever, and an adjusting link connecting said tappct with the stop finger.

9. A portable hoisting apparatus comprising an upright frame, a rearwardly inclined delivery platform arranged at the upper end of the frame, a vertically movable carriage guided onthe frame, a rearwardly inclined lifting platform mounted on the carriage, and arranged on the frontside of the frame and adapted to support a loa nd retaining means for holding the load on the lifting platform while the same is being raised to the level of the delivery platform and then permitting the same to move by gravit from the lifting platform to the delivery platform, including a smp finger movable vertically into and out of the path of the load at the rear side of the lifting platform, a vertically swinging lever pivoted at its front end on the lifting platform and carrying said finger at its rear end, yielding shifting means for holding the lever in a position in which its stop finger projects across the path of the load on the lifting platform, a tappet connected with said lever, and a trip stop connected with the frame and adapted to be engaged by said tappet to move said lever in a direction for withdrawing the stop finger out of the path of the load from the lifting platform to said delivery platform, said lifting platform including stop means for limiting the upward movement of said sto finger and lever relative to said lifting platform.

10. A portable hoisting apparatus comprising an upright frame, a rearwardly inclined delivery platform arranged at the upper end of the frame,

a vertically movable carriage guided on the frame, a rearwardly inclined lifting platform mounted on the carriage, and arranged on the front side of the frame and adapted to support a load, and retaining means for holding the load on the lifting platform while the same is being raised to the level of the delivery platform and then permitting the same to move by gravity from the lifting platform to the delivery platform, including a stop finger movable vertically into and out of the path of the load at the rear side of the lifting platform, a vertically swinging lever pivoted at its front end on the lifting platform and carrying said finger at its rear end, yielding shifting means for holding the lever in a position in which its stop finger projects across the path of the load on the lifting platform, a tappet connected with said lever, and a trip stop connected with the frame and adapted to be engaged by said tappet to move said lever in a direction for withdrawing the stop finger out of the path of the load from the lifting platform to said delivery platform, said yielding shifting means including a helical spring connected at one end with said lifting platform and a screw bolt adjustably connecting the opposite end of said spring with said lever.

11. A portable hoisting apparatus comprising upright frame, a delivery platform projecting rearwardly from the upper end of the frame and provided with conveyor rollers, a vertically movable carriage guided on the frame, a lifting platform mounted on the carriage and arranged on the front side of the frame and adapted to sup port a load, and provided with conveyer rollers, and retaining means mounted on the lifting platform for holding the load on the lifting platform while being raised and permitting the same to pass to the delivery platform when the platforms are on the same level including a vertical stop finger movable vertically into and out of the path of the load between said platforms, and an angular arm having a lower horizontal part arranged below the conveying rollers of the lifting platform and connected with the lower end of said stop finger and a vertical part projecting upwardly from the front end of said horizontal part and pivoted at its upper end on said lifting platform, spring means for raising said stop arm and finger into an operative position, a stop element on the frame, and tappet means adapted to engage said stop element for lowering said arm and finger into an inoperative position.

12. A portable hoisting apparatus comprisin an upright frame, a delivery platform arranged at the upper end of said frame and provided on its front side with gaps, a vertically movable carriage guided on said frame, a lifting platform mounted on said carriage and arranged on the front side of the frame and adapted to support a load, and retaining mean mounted on the lifting platform for holding the load on the lifting platform or releasing the same including stop fingers movable vertically in said gaps into and out of the path of said load from said lifting platform to said delivery platform.

CHARLES A. MARTIN. 

